The NFL Players Association emailed a letter to all agents Tuesday, urging them to begin negotiating player contracts with teams.

In a letter sent by Mark Levin, the NFLPA's director of research, the trade association asked agents to immediately contact teams about any of their players who aren't under contract right now.

The letter states that "unless or until" U.S. District Judge Susan Richard Nelson issues a stay of her ruling to end the NFL-imposed lockout, as the league has asked, the NFLPA believes business should begin now. If a player's contract has expired, the letter states "class counsel believes that you and your agent can start negotiating."

The letter, which provides a primer and a question-and-answer segment about the latest developments in the courts, goes on to state that if a team "refuses" to cooperate in negotiations with a free agent, "you should contact class counsel immediately." The letter also provides appropriate contact information.

NFL general counsel Jeff Pash said in a conference call that the league believes the timing of free agency "really depends on what the scope of the injunction is and whether there is a stay."

"There is a considerable degree of uncertainty about what the scope of the relief is," Pash added.

Pash said there has been some interaction between NFL and NFLPA lawyers regarding some of the uncertainty regarding the start of the league year and rules being put in place. Pash also said the NFL isn't seeking guidance from Nelson on that issue.

"We have not asked Judge Nelson to determine when the new league year will begin," Pash said, adding the NFL "will decide that" once it knows more about the "scope of the injunction."

The NFLPA's class counsel projects a final decision about a possible stay of Nelson's Monday ruling to come "within the next week or so," according to the letter. Pash said both sides expect to hear from the appeals court soon on dates for hearings.

Nelson has given the league until 6 p.m. ET Wednesday to resubmit a request for a clarification on her ruling. The league previously had filed expedited an motion for a stay. Nelson also gave the players until 10 a.m. ET Wednesday to respond to the league's stay request.